286 
The American Geologist. 
May, 1896 
transverse diameter is at the centre and in Temnocyon at the 
posterior end. The heights of p. 3 and i are equal in the former, 
and in the latter species (T. altigenis) the fourth premolar is 
some 4 mm. higher than the third. 
While the preceding premolars are proportionately larger 
than those of FIypotemnodon , in mTl they are of equal size in 
both species, and hence this molar shows greater development 
in the latter or smaller species; the height, however, is less 
than in the type of Temnocyon , and we find, too, that the 
crown is considerably compressed between the proto- and hy- 
poconids. The anterior end of this tooth overlaps the inter¬ 
nal of pTl, but in the type of Temnocyon the teeth are sepa¬ 
rated; the entoconid is more robust in the new genus and is 
separated from the protoconid by a deep groove. The base of 
the protoconid is rather weak, with greater upward curve and 
with more pronounced cingulum as compared with Hypotem- 
nodon. m 72 is proportionately larger and more robust, with 
the protoconid twice the height of that in the new genus; in 
both species the hypoconid is smaller than the protoconid. In 
T. altigenis these two cones are placed along the median line, 
but in the new genus are nearer the external edge, this being 
due to the presence of internal cusps which are not developed 
in Temnocyon. A third tubercular molar is present in Ilypo- 
temnodon , placed internal to the external line of the crown of 
the preceding molars and measures 5 mm. in antero-posterior 
diameter and 3 mm. in transverse. In Temnocyon there is a 
distinct alveolus for this molar, but the tooth itself is absent. 
From the above description it is obvious that Cope’s T. 
coryphaeus (No. 1, p. 906) should be removed from the genus 
Temnocyon and a new genus erected, to which has been given 
the name Hypotemnodon. This genus is represented by the 
cranium and left ramus, which were collected by Dr. J. L. 
Wortman in the John Day Bad Lands of Oregon. 
Authorities Quoted. 
1. Cope, E. D. The Vertebrata of the Tertiary Formations of the 
West, Book 1 (Vol. iii of Hayden’s Survey of the Territories), 1884. 
2. Eyerman, John. The American Geologist, vol. xiv, no. 5. 1894, 
p. 320. 
3. Lartet, H. Bull .Soc. Geol., vol. vii, 1836. 
4. Leidy, Joseph. Extinct Mammalia of Dakota and Nebraska, Jour. 
Acad. Natl. Sci., vii, 2, 1869. 
